Cells can be treated with an electric field in an interior space having a region between two electrodes and receiving a suspension of cells. The cells are exposed to an electric field developed between the electrodes.
A chamber for the treatment of cells with an electric field has been taught in German Patent Document-Open Application DE-OS No. 33 17 415. In this known chamber the space provided for receiving the suspension of cells is formed by a cylindrical shaped inner body and an exterior body surrounding it. Both electrodes are wrapped around the inner body in the shape of a multiple-thread screw so that the region inside of which the cells are treated with the electric field is likewise helicoidal in shape.
In this chamber a very large number of cells simultaneously can undergo treatment by the electric field. However there is a disadvantage since not all of the cells in the region in which the treatment occurs are exposed to the same electric field strength. This increases the variations occurring in the desired product conditioned by the natural distribution of the properties of a cell population. Moreover this chamber is expensive to manufacture.
Another chamber for treating cells with an electric field is described in German Patent Document-Open Application DE-OS 33 21 239. This comprises a base plate with an additional component forming the interior space for the cell suspension and two wire shaped electrodes which project into that space. Of course the chamber is easily manufactured and economical. However the same disadvantage exists as in the previously described known chamber--that is, individual cells may not be exposed to exactly the same electric field strength in the region lying between the electrodes.
Chambers of the above described kind and those with which the invention is concerned can be used for the treatment of cells in an electric field, particularly for the fusion of cells.
One process for fusion of cells is taught in Biochimica et Biophysica Acta, 694 (1982), 227-277 (Electric Field-Mediated Fusion and Related Electrical Phenomena, U. Zimmermann). In this known process -- whose course can be observed under a microscope--a membrane contact between at least two cells is induced by application of a weak alternating uniform electric field.
By the electric field dipoles induced by the polarization, processes in the cells are initiated which cause them to approach one another by their mutual attraction during their random motions through the electrical field (dielectrophoresis).
According to the structure of the cell aggregates or rows the disruption of the membrane structure between adjacent cells is triggered by an electrical rupturing pulsation. (J.Membrane Biol. 67, 165-182 (1982), U. Zimmerman and J. Vienken).
Thus--according to the current concept--holes are produced in the areas of contact of the membranes of adjacent cells which lead to a cytoplasmic continuum between both the cells and to bridge formation of lipids between the membranes of the adjacent cells. The lipid molecule is no longer associated with its original membrane. As soon as a bridge has formed, on the basis of energy considerations a common membrane structure comprising the cells connected with each other by the lipid bridges is formed to restore the lower energy curvature.